Jet-assisted single-phase immersion liquid cooling for heterogeneous chiplet packages: parametric CFD study on flow rate ratio, inlet temperature, and nozzle geometry

초록

This study numerically investigates a jet-assisted single-phase immersion liquid cooling (SPILC) system for high-heat-flux chiplet packages. The system integrates a primary chamber inlet for bulk flow and an auxiliary jet inlet for targeted local cooling of the CPU die (61.2 W/cm2, 7 × 7 mm2). Three-dimensional steady-state CFD simulations using the Realizable k-ε turbulence model examined the effects of flow rate ratio (β = QInlet2/QInlet1), inlet fluid temperature, and jet nozzle geometry. Relative to conventional SPILC under the same total flow rate, jet impingement at β = 1 reduced CPU temperature by 6.11 K. As β increased from 0 to 3, the maximum CPU, GPU, and memory temperatures decreased by 16.18 K, 5.08 K, and 6.97 K, respectively, while the heat transfer coefficient improved by 42.35%. PEC analysis identified β = 3 as the Pareto-optimal operating condition. A Nusselt number correlation, Nu = 3.209 · Rejet0.454 (R2 = 0.994, 3058 ≤ Rejet ≤ 6877), was derived and shown to be physically consistent with limiting-case correlations for forced convection and jet impingement reported in the literature. This correlation is valid within the ranges of Reynolds numbers, fluids, and geometric conditions tested in this study. Inlet temperature variation produced a proportional shift (∼5 K per 5 K change) without affecting flow-side performance, confirming thermal-hydraulic decoupling. The multi-nozzle configuration (Shape 2: five nozzles, d = 0.9 mm) achieved up to 17.07% higher heat transfer coefficient and 3.25 K lower CPU temperature than the single-nozzle baseline (Shape 1: d = 2 mm) under equivalent Reynolds number conditions, at the cost of up to 532% higher pumping power. These findings provide quantitative design guidelines for jet-assisted SPILC systems targeting next-generation chiplet thermal management. Copyright © 2026. Published by Elsevier Masson SAS.

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